Hydraulically operated grinding machine



W. H. WOOD HYDRAULICALLY OPERATED GRINDING MACHINE pril 27, 1937.

Filed April l, 1936 2 Sheets-Sheet 1 W. H. WOOD HYDRAULICALLY OPERATEDGRINDING MACHINE Filed April l, 1936 2 Sheets-Sheet 2 www www WN Nu m xWHLLHDE H. VVDUB Mw. www,

Patented Apr. 27, 1.937

UNITED STATES PATENT OFFICE Wallace H. Wood, Worcester,

Mass., assignor to Norton Company, Worcester, Mass., a corporation ofMassachusetts Application April 1, 1936, Serial N0. 72,115

7 Claims.

'Ihis invention relates to grinding machines, and more particularly to ahydraulically operated cylindrical grinding machine.

' One object of this invention is to provide a 5 simple and thoroughlypractical hydraulically driven cylindrical grinding machine. A furtherobject of this invention is to provide an improved hydraulicallyoperated table reciprocating mechanism for the reciprocable table of acylindrical grinding machine.

A further object of this invention is to provide a simplified valvecontrol unit which serves not only to control the table movement butalso vthe wheel feeding movement. A further object is to provide areadily controllable dwell control mechanism for controlling the extentof dwell at each end of the table reciprocation. Other objects will bein part obvious or in part pointed out hereinafter.

'This invention accordingly consists in the features of construction,combinations of elements, and arrangements of parts, as will beexempliedv inthe structure to be hereinafter described, and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown one of various possibleembodiments of the mechanical features of this invention,

Fig. 1 is a front elevation of the improved 30 grinding machine, havingparts broken away and shown in section to more clearly show theconstruction;

Fig. 2 is a diagrammatic view, showing the valve and piping diagram ofthe hydraulic table reciprocating and wheel feeding mechanism;

Fig. 3 is a fragmentary vertical cross sectional View, on an enlargedscale, taken approximately on the line 3 3 of Fig. 1;

Fig. 4 is a fragmentary vertical section, taken approximately on theline 4 4 of Fig. 3;

Fig. 5 is a fragmentary detail view of the control for the reverse andtraverse valves, on an enlarged scale, taken approximately on the line 55 of Fig. 3; and

Fig. 6 is a fragmentary vertical section,l on an enlarged scale, takenapproximately on the line 6 6 of Fig. 3, showing the connection betweenthereversing and wheel feed control valve.

A grinding machine has been illustrated in the drawings comprising abase :I which supports a transversely movable wheel slide II thereon.The wheel slide II is mounted for a transverse movement'on a V-way (notshown) and flat way in a mannerv similar to that shown 3 in the expiredpatent to`Norton No. '762,838 dated June 14, 1904. The wheel slide IIsupports a rotatable grinding Wheel I2 on a rotatable wheel spindle I3.The wheel spindle I3 may be rotated by means of an electric motor I4mounted on the upper surface of the wheel slide. The motor is providedwith a rotor shaft I which is provided with a pulley I 6 connected by abelt I1 with a pulleyv I8 mounted on the wheel spindle I3.

The base I0 also supports a longitudinally reciprocable work table onV-way and flat way I9, as indicated in the above-mentioned expired priorpatent to Norton. The table 25 serves to rotatably support a cylindricalwork piece 26 on a headstock 21 and a footstock 28. The headstock 21 isprovided with a, headstock center 29 and the footstock 28 is providedwith a footstock center 30 which are arranged to engage center holes inthe opposite ends of a work piece to rotatably support the same during agrinding operation. The headstock 21 is provided with a rotatable faceplate 3I which may be driven .from any suitable source of power, such asa motor on the headstock or an overhead belt drive. 'I'he plate 3Icarries a driving pin 32 which engages a dog 33 mounted on the end ofthe work piece 26 25 to rotate the work piece for a grinding operation.

Wheel feed The wheel slide II may be fed transversely relative to thebase I0 by' means of a half nut (not shown) and a rotatable feed screw35 which is rotatably supported in bearings (not shown) in the base I0.These parts have not been shown in detail. since they are not consideredpart of the present invention. For further details of 3 constructionofthis nut and screw mechanism, reference may be had to theabove-mentioned prior patent to Norton No. 762,838. The outer end of thefeed screw 35 carries a gear 36 meshing with a small gear 31 rotatablymounted on a shaft 38. A feed wheel 39 is also rotatably supported onthe shaft 38 and is either formed integral with the gear 31 or rigidlyfastened thereto so that when the hand wheel 39 is rotated, a rotarymotion will be transmitted through the gear 31, the gear 36, to rotatethe feed screw 35 so as to cause a transverse -feeding movement of theslide II and grinding wheel I2 either toward or from the work piece 26,depending on the direction of rotation of the feed wheel 39. 50 The feedwheel 39 may be rotated manually, if desired. A micrometer adjustingmechanism 40 is provided on the hand wheel 39 and carries an abutment 4Iwhich isvarranged in the path of a feed pawl 42 which is pivotallymounted on 55 a stud 83. The micrometer` adjusting device 38 facilitatesthe resetting of the stop abutment 8| relative to the feed wheel 88 tomake compensation for wheel wear to accurately size the work 5 piece.The feed pawl 82 is preferably arranged for a reciprocatory motion toengage the teeth of thefeeol wheel t8 so as to cause an automaticinfeeding movement of the grinding wheel when desired. The movement ofthe feed pawl i2 is preferably accomplished by means of a fluid pressuremechanism including a cylinder '88 which contains a slidably mountedpiston 35. A piston rod 86 is formed integral with the piston l5 andcarries at its upper end a bracket l1 which serves as a support for thestud 53. It is desirable to provide a suitable means for adjusting` theextent of movement of the feed` pawl 82. This may comprise an adjustablestop screw i8 which is carried by a projecting lug 99 on the base |8.The stop screw i8 is arranged in the path of a projecting portion of thebracket l1 carried bythe piston i6 so that the upward movement of thepiston |55 together with the upward movement of the pawl i2 may bevaried wheel 89 may be picked up at each reciprocation of the feed pawl82.

Table reciprocatz'on.

The longitudinally movable work table 25 is slidably mounted on V andflat ways (not shown) and is arranged to be automatically reciprocatedlongitudinally relative to the base |8 so as to reciprocate the workpiece 28 'in operative relation with the grinding wheel i2. Thereciprocating mechanism preferably `comprises a hydraulic systemincluding a cylinder 55 which is flxed to the under side'of the table525. The cylinder 55 contains a pair of spaced pistons 56 and 51 whichare connected by hollow piston rods 58 and 59 respectively,l withsupporting brackets 68 and lrespectively which are rigidly mounted onopposite ends of the base i8. A fluid pressure reversing valve 65 isprovided to control the admission of iluid under pressure to cylinderchambers 62 and 63 respectively, at opposite ends of the cylinder 55.The reversing valve 65 is preferably of a piston type in which a.plurality of valve pistons 66, 61, 68 and 69 are formed integral withthe valve stem 65. v

Fluid under pressure is supplied by means of 'f a pump 15 which ispreferably located within the base I8. The pump 15 draws iiuid through apipe 16 from a reservoir or sump 11 which is also located within thebase |8v vand forces fiuid through a pipel 18, a passage 19\within avalve casing 18, and through a passage 88 into avalve chamber 8| locatedbetween the valve pistons '66 and 61 and through a. passage 82 into avalve ochamber 83 located between the valve pistons 68 and 69. -In theposition of the parts, as illustrated in Fig. 2, Afluid under pressureenteringl the valve 'chamber 8| passes out through a passage 84, througha ypipe 85, and through a central aperture 86 within the piston rod 58and into the cylinder chamber 62 to cause the cyl- ,inder 55 and thetable 25 to move toward the left, as viewed in Fig. 2.y Duringtheadmission of fluid under pressure to the cylinder chamber 62, fluid isexhausted from the cylinder chamber 63 through a central aperture 88within the piston rod 59, through a pipe 89, a passage 98 within. thevalve casing 8, into a valve chamber 9|, and exhausts therefr m througha passage 92. In order to automatilcally control the moveas desired sothat one or more teeth of the feed aoravae ment of the reversing valve65, a pilot valve 98 is provided which is automatically actuated intimed relationship with the table movement to cause a reversal in thedirection of movement of iiuid under pressure. As illustrated in Fig. 2,the pilot valve is preferably of a piston type comprising a valve stem|88 having formed integral therewith valve pistons |8l, |82, |83 and|88. The fluid under pressure from the pump l5 and pipe 18 passesthrough a passage |85 into a valve chamber |88 formed between the valvepistons |82 and |83. When the pilot valve is shifted toward the right(Fig. 2), fluid under pressure entering the valve chamber |86 passesoutwardly through a passage |81 into a valve .4

chamber |88 in the reversing valve 65 formed between the valve piston 69and the end of the valve casing. Fluid under pressure entering thechamberl |88 serves to move the reversing valve toward the left (Fig.2). This movement of the reverse valve 65 toward the left causes valvepiston 61 to close the passage 8d and after a further movement of thevalve, shifts the valve ypiston 68 so that iiuid under pressure from thepassage 82 into valve chamber 83 passes through passage 98 and pipe 89into the cylinder chamber 63 to cause the cylinder 55 and table 25 tostart moving toward the right, as viewed in Fig. 2. y

In grinding a cylindrical work piece, itis desirable to provide a dwellat the en`d of the reciprocatory stroke in order that the work piece maymake at least one complete rotation while the grinding wheel is attheend of its reciprocatory stroke in order that the grinding wheel maygrind completely around the work piece to grind the same to a truecylinder before the work piecesta'rts moving in the reverse direction.The extent of dwell is preferably regulated by a needle valve ||8 in thepassage |81 which serves to regulate the fluid passing through thepassage |81 and thereby regulates the speed of shifting of the reversevalve 65.r

Similarly, when the pilot valve stem |88 is moved toward the left, asviewed in Fig. 2, fluid under pressure entering the chamber |86 passesoutwardly through a passage ||2 into a valve chamber ||3 which is formedbetween the valve piston 66 and the en'd of the valve casing. Admissionof fluid under pressure to the chamber I3 serves to move the reversingvalve 65 toward the right, into the position illustrated in Fig. 2, soas to reverse the direction of flow of fluid within the system. A needlevalve ||4 is provided in the passage I2 and serves to regulate thepassage of, uid under pressure through the passage ||2 and consequentlyregulates the speed of movement of the reverse valve 65 toward the rightso as to control the extent of dwell when the table is at the end of isreciprocatory stroke. By adjusting the needle valves ||8 and I4, theextent of dwell at each end of thetable stroke may be varied, asdesired.

When the pilot valve 99 is in the position as illustrated in Fig. 2,fluid within the valvephamber |88 may exhaust through passage |81,passage ||6, intovalve chamber ||1, and through a passage ||8, intdavalve chamber ||9, and out` through a passage\|28 and an exhaust pipe|2| into the reservoir 11.

"Similarly, fluid within the valve chamber ||3 may exhaust through thepassage ||2, a. passage |23, into a valve chamber |24, through a passage|25, into a valve chamber |26, and out through |34 with a groove |35 inan end a passage |21 voir 11.

The pilot valve 99 is normally maintained'in a central position, asindicated in Fig. 2. A yieldable device including a pair of opposedsprings is utilzed to maintain the pilot valve in its neutral or centralposition. A bell crank lever |30 is rotatably mounted on a stud |3|which is fixedly mounted relative to the base |0. The bell crank |30 hasan upwardly extending arm |32 which is connected by means of a stud |33and a roller block 36 which is flxedly mounted on the end of the valvestem |00. In the preferred construction, the stud |3| together with thevalve actuating mechanism is supported in an apron 31 which is xedlymounted on the base I0. The forward end of the bell crank member |30 isprovided with outwardly extending arms |38 and |39 which extend atsubstantially right angles to the arm |32. The arms |38 and |39 carryadjustable stop screws |40 and |4| respectively which bear against thelower ends of a pair of vertically arranged slidable rods |42 and |43.The rods |42 and |43 are slidably supported in the apron 31. The bellcrank |30 v and the valve 99 are held in a central position, asindicated in the drawings, by means of a pair of springs |45 and |46which surround reduced end portions |41 and |48 of the rods |42 and |43respectively. Collars |49 and |50 are xedly mounted on the lower ends ofthe portions |41 and |48 of the rods 42 and |43, and the springs |45 and|46 are interposed between the fixed collars |49 and |50 and a pair ofslidably mounted collars |5| and |52 which are located on the portionsv|41 and |48 of the rods |42 and |43 respectively. By adjusting thescrews |40 and |4|, the tension of the springs |45 and |46 may beadjusted or balanced to normally hold the bell crank |30 and the valve99 in the central or neutral position as indicated in Fig. 2.

In order to automatically actuate the pilot valve 99 in timed relationwith the table movement, a pair of adjustable dogs and |56 areadjustably supported in a T-slot |51 formed in the front edge of thetable 25. The dogs |55 and |56 are preferably staggered (Fig. 3), thatis one of the dogs projects forward to a greater extent than the other.The dog |55 is arrangedin the path of a roller |58, and the dog |56 isarranged in the path of a roller |59 so that when the dog |55 or |56engage either the roller |58 or |59, the dogs will transmit a downwardmovement to one of the rollers |58 or |59 which serves through rods |42or |43 to rock the bell crank |30 and thereby shiftthe pilot valve stem|00 from a central position, as indicated in Fig. 2.

The rollers |58 and |59 are rotatably supported on the upper ends ofvertically extending plungers |60 and |6| respectively. Ihese plungers|60 and |6| are slidably mounted within sleeves |62 and |63respectively. The sleeves |62 and |63 are preferably removably mountedwithin the apron |31 so as to facilitate adjustment of the mechanism. Inorder to prevent the plungers |60 and |6| from turning within theirrespective sleeves |62 and |63 and the apron |31, and in order tomaintain the rollers |58 and |59 always in operating position withrespect to the dogs |55 and |56, each of the plungers |'60 and |6| isprovided with a keyway |64 and |65 respectively. A screw |61 is mountedin the apron |31 and has a projecting end portion which passes through ahole in the sleeves |62 and |63 and engages the keyways |64 and |65 inthe plungers |60 and IBI and the pipe 12| into the reserrespectively.Only one of the screws |61 has been illustrated in Fig. v3 as passingthrough the sleeve |63 and engaging the keyway |65. A similar screwpasses through the apron 31 andrthrough sleeve |62 and engages thekeyway |64 to hold the plunger |60 against rotation. The plungers |60and 6| are provided at their lower ends with adjustable stop screws |68and |69 respectively `which are screw threaded into the ends of theplungers and are held in adjusted position relative thereto by means oflock nuts |10 and |1| The heads of the screws |68 and |69 bear againstthe upper end surfaces of the rods |42 and |43 respectively. Theplungers |60 and |'6| may be readily removed from the apron |31 byremoving the screws |61 and withdrawing the plunger |60 and |6| togetherwith its supportingl sleeve I 62 and |63 vertically from the apron. Theadjusting screws 68 and |69 may then be readily adjusted so that whenthe plungers |60 and |6| are assembled in the machine, the rollers |58and |59 will project vertically to the desired extent with relation tothe dogs |55 and |56 respectively.

Whenl the table 25 is moved longitudinally, as shown in the drawings,the longitudinal movement continues until the dog 55 or |56 engages theroller |58 or |59 respectively and the dog serves to move the roller andplunger downwardly so as to rock the bell crank |30 against the tensionof the spring |45 or |46 to move the pilot valve stem |00 from a centralposition and to admit fluid under pressure to either the end chamber |08or the end chamber I3 in the reversing valve 65 so that the valve isthereafter shifted into a reverse position by fluid under pressure.

It is desirable that the reversing valve 65 be moved quickly when thetable reaches the end of its stroke so as to stop the table movement.This is preferably accomplished by providing an interconnection betweenthe pilot valve 99 and the reversing valve 65 so that during the initialmovement of the pilot valve by means of the dogs |55 and 56 and rollers|58 and 59, the reversing valve will be positively shifted to cut offthe exhaust of fluid from the system so as to stop the table movement.This is preferably accomplished by means of a rock arm |15 which ispivotally mounted on a stud |16. One end of the rock arm |15 isconnected by a stud |11 with a groove |18 in the head valve stem |00.The other end of the rock arm |15 is provided with a stud |19 which isarranged to engage either the collar or a collar 8| which are mounted onthe end of the reverse valve stem 65. As indicated the stud |19 is inengagement with the collar |80. When the table reaches theend of itsstroke, that is so that the dog |56 moves the roller 59 downwardly-torock the bell crank 30 in a clockwise direction (Fig. 4) it serves toshift the pilot valve stem 00 toward the right (Fig. 2). This movementalso serves through the rock arm |15 to move the stud |19 in acounterclockwise direction (Fig. 2) toward the left so as to shift thevalve '65 toward the left (Fig. 2) and thereby cause the valve piston 68to cover the passage 90 to stop the table movement. This movement of thereverse valve is caused directly by the adjustable dog |56 on the tableand roller |59 through the bell crank |30 and rock arm |15. The movementof the valve stem |00 toward the right (Fig. 2) serves to move the valvepiston |03 so as to uncover the passage |01 and admit uid under pressureinto the valve chamber |08 to complete the movement of the reversingvalve by the controlled influence |36 xedly mounted on the end of the inFigs. 2, 5 and 6,

Cal

of fluid under pressure. By regulating the admission of fluid underpressure into the chamber |99, the extent of `dwell of the table at theend of its stroke may be varied, as desired.

Similarly, when the reverse valve 65 .is at the other end ofthe tablestroke, the stud |19 engages the collar |8| mounted on the end of thevalve stem 65, so that when the dog `|55 engages the the roller |58 androcks the bell crank 199 in a counterclockwise direction to shift thepilot valve toward the left (Fig. 2), this movement serves through rockarm |15 and stud H19 to move the collar |B| toward the right (Fig. 2) toagain shift the reverse valve 65 to cut off the exhaust of fluid fromvthe system and admit fluid under pressure from the valve chamber |96,through the passage H2, the needle valve Hit, into the reverse valvechamber H3, to again shift the reversing valve into the positionillustrated in Fig. 2.

The reversal of the table movement may be readily controlled by varyingthe shapeof the cam surface formed on the lower operative faces of theadjustable table dogs v|55 and B56. By varying the shape of the dogfaces, the pilot valve and the reversing valve may be moved at acontrolled rate to cut oif the supply of iluid and stop the tablemovement in one direction before the valve is shifted into a reversedirection, as controlled by the pilot valve. Thus, either an abruptstopping of the table movement or a gradual slowing down may beobtained, as desired. v

It is desirable to provide a manual control for the reversing mechanismso that the table 25 may be manually reversed in its direction ofmovement when desired. In the preferred construction, a manuallyoperable control Vis provided to shift the reversing Valve 65. Amanually operable control lever is mounted on the outer end of a rockshaft |86, which is rotatably supported in a portion of the apron |31.The inner end of the rock shaft |86 is provided with a downwardlyextending arm |81 having a stud |88 engaging a groove |89 in aconnecting member |99 which is xedly mounted on the valve stem 65between the collars |89 and IBI. By shifting the lever |85 either towardthe right or toward the left, the reversing valve 65 may be readilyshifted to change the directio-n of movement of the table 25 under theinfluence of fluid pressure.

Asuitable speed controlling mechanism is provided for -the tablemovement so that the speed of reciprocation of the table may be readilyadjusted to a desired speed for grinding. This is preferablyaccomplished by means of a control valve |99. This val ve is preferablyof a piston type and is preferably arranged to control the exhaust offluid from! the system. As illustrated in Fig. 2 of the drawings, fluidunder pressure exhausting froml the cylinder chamber 63 through thepassage 86 in the connecting rod 59, through the pipe 89, the passage99, and valve chamber 9 I, passes outwardly through a passage 92 and aport |9| into a valve chamber |92 and through a pipe |93 which exhaustsinto the reservoir 11.

The control valve |99 preferably comprises a pair of spaced pistons |94and |95 which are preferably formed integral with a valve stem |91. Theend |96 of the piston |95 is slabbed off at an angle relative to theaxis of rotation of the piston and is arranged to throttle the fluidpassing through the port |9| when the valve |99 is moved toward the left(Fig. 2). By rotating the valve piston |95, the aperture of the port |9Imay be varied so that the speed of the table may be varied from, amaximum to a mnimumi speed.

v acreage The valve stem '|91 carries at its outer end an adjusting knob|98 which is provided with a dial 899 cooperating with an index linger299 to locate the valve in the desired rotary position for producing therequired table speed. The index ilnger 299 is carried by a sleeve 29|which fits on the valve stem |91 and is held against rotation by meansof a manually operable control lever 292. The control lever 292 ispivotally mounted on a'stud 293 carried by a bracket 299 fixed to thebase of the machine. In the full line position of the valve |99 and thecontrol lever 292, as shown in Fig. 2, the table 25 is reciprocating ata maximum; speed. By rotating the valve control knob E98, theslabbed-oif portion may be turned to close a portion of the port |9| toslow down the table movement. When it is desired to stop the tablemovement, the valve control lever 292 is movedfrom the full lineposition into the dotted line position 292a (Fig. 2) so that the valvepiston closes the port |9|,

thereby stopping the exhaust offluid from the chamber 63 and stoppingthe movement of the table 25. At the same time, a valve chamber 295located between the valve pistons |99 and |95 is moved into the dottedline position (Fig. 2) which serves to connect a passage 296 with a pipe291 so that fluid may by-pass inder chamber 62 into the cylinder chamber63 when the table is traversed manually by mecha- Y nism to behereinafter described. The fluid may by-pass from the cylinder chamber62 through the passage 86 in the piston rod 58,.-through a pipe 95,through the passage 296, valve chamber 295, and pipe 291, into pipe 89,through the passage 99 within the piston rod 59 and into the cylinderchamber 63, thus forming a free passage of fluid between the oppositeends of the cylinder.

In the dotted line position 292a of the control lever 292, the table 25may be traversed longitudinally by a manually operable traversemechanism without the necessity of overcoming the fluid pressure withinthe system due to the bypass of fluid above described. A manuallyoperable traverse mechanism has been illustrated comprising a rack bar2| 9 depending from the under surface of the table 25. A gear 2|| whichis rotatably mounted on a shaft 2|2 meshes with the rack bar 2| 0. Theshaft 2| 2 also carries a large gear 2| 3 which xed to the gear 2| Thegear 2| 3 meshes with a small gear 2|4 rotatably supported on a shaft2|5 and fixed to a hand wheel 2|6. By rotating the hand wheel 2|6 ineither direction, a rotary motion is transmitted through the gear 2|4,2|3 and 2|| to move the rack bar 2|9 endwise and to impart acorresponding traversing movement to the table 25.

The wheel feeding mechanism above described is preferably interconnectedwith the iiuid pressure table reciprocating mechanism so that theinfeeding movement of the grinding wheel takes place at the end of areciprocatory stroke of the table. As illustrated in Fig. 2, fluid underpressure from the pipe 16'passes th'rough a pipe 2|1 into a cylinderchamber 2|8 above the piston 45. The cross sectional area of the pistonrod 46 is relatively large compared with the cross sectional area of thepiston 45, thereby producing a differential effective area on the upperand lower surfaces of the piston 45. The effective area of the lowersurface of the piston45 is greater than'l the effective area of theupper surface thereof and serves to cause an upward movement of thepiston 45 when fluid under pressure 'from is either integral with orfrom the cylthe samie source is admitted to a lower cylinder chamber2|9. The piston 45 is normally held in a down position by the continuoussupply of uid pressure entering the cylinder chamber 2| 8.

In order to produce a controlled infeeding movement, a feed controlvalve is provided forl controlling the admission of uid to the cylinderchamber 2|9. A wheel feed control valve 220 of the balanced piston typeis provided comprising a valve stem 22| having formed integrallytherewith valve pistons 222, 223, 224 and 225. In order that the infeedof the grindingwheel I 2 may take place during the period of reversal,it is desirable that the control valve 220 be operated in timed relationwith the reversing valve 65. As illustrated in the drawings, this ispreferably accomplished by connecting the valve stem 22| with the valvestem 65, preferably by means of a link 226 which is rigidly xed to thestems of each of said valves so that when the reversing valve 65 isshifted to reverse the direction of movement of the table 25, fluidunder pressurefrom' the vpassage |05 passes downwardly through a passage221 which, as shown in Fig. 2, is blocked by the.

valve piston 223. When the reverse valve 65 starts moving toward theleft (Fig. 2), the valve stem 22| is also moved toward the left by meansof the link 226. After the valve vstem moves toward the left asufiicient distance to Vuncover the passage 221, fluid under pressuremay pass for an instant through a valve chamber 228 and out through aApipe 229 into 'the valve chamber l2| 9, thereby causing a differentialpressure which is greater on the under surface of the piston and servesto move the piston upwardly, carrying the feed pawl 42 to move it idlyover the feed wheel 39. 'I'he passage of uid to the chamber 2|9 ispermitted only for an instant, after which the valve piston 224 closesthe port admitting fluid to the pipe 229, and fluid under pressurewithin the pipe 229 and cylinder chamber 2|9 may then exhaust through avalve chamber ||9 and out through a passage |20 and pipe |2| into thereservoir 11. y

On the reverse movement of the valve stem 22|, fluid under pressure isadmitted instantaneously through the pipe 229 to cause an infeedingmovement of the wheel at the other end of the table stroke. When thevalve piston 224 cuts loff the ow of fluid through the pipe 229 andallows the uid within the cylinder chamber 2|9 and pipe 229 to exhaustthrough the valve chamber |26 and passage |21 into the reservoir 11, thecontinuous fluid under pressure applied through the pipe 2|1 causes thepiston 45 to again move downwardly, causing the feed wheel 39 to rotatein a counterclockwise direction to cause an infeeding movement of thegrinding wheel I2.

'I'he operation of the machine is readily apparent from the foregoingdisclosure. A work piece 26 is mounted on centers 29 and 30 and the workand wheel are started in rotation. The table dogs |55 and |56 are thenlocated along the front edge of the table' 25 within the T.slot |51 sothat the table may be reciprocated to pass the desired por'- tion of thework piece 25 across the operative face of the grinding wheel |2. Theknob |90 is then rotated to the desired table speed and the ycontrollever 202 is moved from the dotted line position 202a (Fig. 2) into thefull line position to start the table reciprocation. 'I'he adjustablestop screw 48 may then be adjusted so that the desired movement of thefeed pawl 42 may be obtained to cause either one or more teeth on thefeed wheel to be picked up at each reciprocation of the feed pawl. 'I'hespeed of movement of the lfeed pawl in an upward direction may bereadily adjusted by means of an adjustable valve 23| which is locatedbetween the pipe 229 and the cylinder chamber 2|9. Similarly, theadmission of continuous uid under pressure to the cylin- .der chamber2|8 may be controlled by a valve 232 so that the speed of movement ofthe feed pawl 42 in either direction may be independently adjusted, asdesired. 'Ihe needle valve ||0 and ||4 may then be adjusted to vary theextent of dwell at each end of the table reciprocation in order that thework piece may rotate at least one complete turn at the end of the tablestroke before the table starts its movement in the reverse direction.

It will thus be seen that there has been provided by this invcntionapparatus in which the various objects hereinabove set forth togetherwith many thoroughly practical advantages are successfully achieved. Asmany possible embodiments may be made of the aboveinvention and as manychanges might be made in the embodiment above set forth, it is to beunderstood that all matter hereinbefore set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.

I claim:

1. A grinding machine comprising a transversely movable rotatablegrinding wheel, means including a piston and cylinder to feed said wheeltransversely, a longitudinally movable work supporting table, meansincluding a piston and cylinder to reciprocate said table, a fluidpressure system including a pump, a reversing valve to change thedirection of fluid pressure to said cylinder, a pilot valve to controlthe movement of said reverse valve, a bell crank lever operativelyconnected to said pilot valve, a pair of balanced springs to hold saidlever and valve in a neutral or central position. a pair of movableplungers carried by said base which are operatively connected to actuatesaid lever and valve, adjustable staggered dogs on said table, and aroller on each of said plungers, each of which is arranged in the pathof one of said dogs.

2. A grinding machine comprising a transversely movable rotatablegrinding wheel, means including a piston and cylinder to feed said wheeltransversely, a longitudinally movable work supporting table, a fluidpressure system which is arranged to reciprocate said table including apair of adjustable staggered dogs on said table, a pair of plungerscarried by said base each of which is arranged in the path of one ofsaid dogs, a pilot valve which is normally held in a central or neutralposition and which is actuated in either direction by one of saidplungers, a reversing valve which is operatively connected to reversethe direction of fluid in said table cylinder, and connections betweensaid pilot valve and reverse valve whereby movement of either of saidplungers serves to move the re- 'verse valve to stop the table movementand fluid from the pilot valve serves to complete the movement of thereverse valve to start the table moving in the reverse direction.

3. A grinding machine table reciprocating mechanism comprising alongitudinally movable table, a piston and cylinder operativelyconnected to reciprocate said table, a reversing valve arranged tocontrol the admission of fluid to said cylinder to reverse the directionof movement of said table, a control valve which serves to throttle theexhaust of iiuid from said cylinder,

a pair of adjustable oiiset dogs carried by said table, a verticallymovable plunger associated with each of said dogs, a pilot valveactuated by said plunger, lost motion connections between the pilotvalve and the reverse valve whereby the initial movement of the pilotvalve serves to positively shift the reverse Valve through a sufcientdistance to cut E the exhaust of iiuid from said cylinder, andcontrolled means nterposed between the-pilot valve to convey controllediiuid under pressure to complete the shifting of the reverse valve.

4. A grinding machine comprising a rotatable grinding wheel, atransversely movable slide to support said wheel, a pawl and ratchetfeed mechanism therefor, means includingl a piston and cylinder toactuate said pawl and ratchet,

a control valve therefor, a longitudinally reciprocable table, meansincluding a piston and cylinder to reciprocate said table, a pair ofadjustable offset dogs on said table, a pair of vertically arrangedplungers each of which is aligned with one of said dogs, and meansincluding a control valve mechanism actuated by said plungers to controlthe reciprocation of said table and the infeed of the grinding wheel.

5. A grinding machine comprising a rotatable grinding wheel, atransversely movable slide to support said wheel, a pawl and ratchetfeed mechanism therefor, means including a piston and cylinder toactuate said pawl and ratchet, a control valve therefor, a.longitudinally reciprocable table, means including a piston and cylinderto reciprocate said table, a pair of adjustable oifset dogs on saidtable, a pair of vertically arranged plungers each of which is alignedwith one of said dogs, means including a control valve mechanismactuated by said plungers to control the reciprocation of said table andthe infeed of the grinding wheel, and connections between said tablecontrol valve and said feed control valve whereby the feed control valveis operated by and in timed relation with the table control valve tocause an nieeding movement of the grinding wheel duringthe period ofreversal. t

6. 1n a grinding Amachine, a longitudinally movable table,v a piston andcylinder operatively connected to reciprocate said table, a kpair ofadjustable offset dogs carried by said table, a pair of plungers, aroller on the upper end of each of said plungers which is aligned withone of said dogs, a reversing valve to control the admission and exhaustof fluid from said cylinder, means including a pilot valve which isactuated by said dogs and plungers to shift the reversing valve, andindependent adjustable connections between each of said plungers andsaid pilot valve whereby movement of one of said plungers serves toactuate the pilot valve in one direction to reverse the movement of thetable and depression of the second plunger serves to move the pilotvalve in the opposite direction to again shift the direction of movementof the table.

7. In a grinding machine, a longitudinally Y movable table, a piston andcylinder operatively connected to reciprocate said table, a pair ofadjustable oifset dogs carried by said table, a pair of slidably mountedplungers, a roller on the upper end of each plunger which is arranged inthe path of one of said dogs, a reversing valve to control the admissionand exhaust of fluid from said cylinder, means including a pilot valveto shift said reverse valve, means including a bell crank lever toactuate said pilot valve, and adjustable connections between each ofsaid plungers and said lever whereby engagement of one of said dogs withits respective' roller serves t depress the plunger and actuate thepilot valve in one direction and engagement of the second dog with thesecond roller serves to depress the second plunger to actuate the pilotvalve in the reverse direction to control the reversal of the tablemovement.

WALLACE H. WOOD.

